The recording industry has gone through a number of technologies, successors either affording greater convenience to the user such as longer playing time, and preferably duplicating the live performance more faithfully. Yet even the latest technology has some sort of defect, which the human ear, being a precise instrument, interprets as lack of realism. Defects in the earliest recordings, specifically Edison cylinders and 78 RPM records, comprise foreign particles or scratches in the recording matrix which upon playback produce discrete clicks or pops, and graininess in the recording matrix which is visible under magnification, which upon playback produces high frequency “hiss.” With the advent of long play 33⅓ RPM record and magnetic tape, the issue of foreign particles was substantially eliminated, but these media are still susceptible to graininess producing hiss and high frequency distortion during playback. With the advent of the compact disc, the graininess issue was resolved by digital recording techniques but the low sampling rate resulted in limited bandwidth whose sound some have characterized as having sterility or lack of presence. Another type of defect detracting from aural realism involves the compromises in microphone placement utilized in detecting the sound. Microphones that are distant from the origin of the sound are overly sensitive to hall echo. Attack transient components such as produced by the hammer strike of a piano or speech utterance, become blurred. Use of a close microphone alone might improve attack transients, but commensurate use of multi-microphoning to rid the recorded sound of unnatural dryness results in a plurality of mixed phases that likewise have a blurring effect. In either case of microphoning, the sense of space that was present in the live performance is sacrificed, whereby sound transients are muted that otherwise enable the listener of the live performance to spatially locate the origin of the sound. Another cause of blurring is the use of multiple loudspeakers, increasingly common in live music concerts, public theaters, or home theaters. Multiple loudspeakers and the various distances between the loudspeakers and the listener result in a complex array of phases compounded by reflections in the listening hall. The listener is aware of a surround-sound effect but the use of multiple loudspeakers does not improve and may even interfere with spatial location discernment. Another cause of high frequency overtone or attack transient loss is in the wireless transmission of sound where high frequencies and attack transients are deliberately removed from the transmitted signal in order that the transmission does not interfere with another wireless transmission being broadcast at a nearby carrier frequency. Yet another cause of high frequency overtone or attack transient loss is mechanical inertia associated with microphone or loud speaker diaphragms, cutting or reproducing styli, or the like.
The prior art includes devices that alleviate defects in the recording, re-enforcement, or playback of live performances. The applicant is co-patentee of U.S. Pat. Nos. 4,155,041; 4,151,471 and 4,259,742 and is sole patentee of U.S. Pat. No. 4,322,641 and co-pending U.S. patent application Ser. No. 09/286,575. These references disclose three distinctly different and complementary systems for eliminating or reducing defective sound in the playback of old cylinder and disc records. The first of these systems eliminates clicks and pops in the reproduction of monophonic disc or cylinder records by virtue of a switching process that selects reproduction from the momentarily quieter groove wall or from an equal mixture of the two, requiring that the recording be reproduced with two-track, stereophonic equipment. The second of these systems eliminates or greatly reduces the amplitude of clicks and pops that remain after the switching process. The third system reduces the high frequency “hiss” that is not susceptible to reduction by the first and second systems. The second and third systems are applicable to both monophonic and multiple channel recordings. Prior art devices do not compensate for absence of overtones or attack transients, one or both sound characteristics being necessary ingredients for aural realism. These features are missing even in today's highly regarded technology comprising but not limited to compact discs, multiple microphoning, multiple loud speakers, direct video discs (DVD's), and wireless transmission.